Thermoplastic resins are generally characterized by their many advantageous properties which include optical clarity, high ductility, high heat deflection temperature as well as dimensional stability. As a result of such properties, they are often employed in many commercial applications.
While thermoplastic resins possess the above-described advantageous properties, they often display low abrasion and chemical solvent resistances, and like many other organic polymeric materials, they are susceptible to photodegradation by ultraviolet light. The photodegradation typically results in unfavorable characteristics including yellowing and erosion of the resin surface.
Diacyl resorcinols, particularly dibenzoyl resorcinols, have been found to be effective light stabilizers in polymer resins. Typically, dibenzoyl resorcinols are prepared by treating dimethoxybenzene with benzoyl chloride in the presence of at least stoichiometric amounts of anhydrous aluminum chloride in an organic solvent. However, such a method is not very favorable, since among other reasons, it results in the release of environmentally unfriendly organic volatiles and requires disposal of large amounts of excess aluminum chloride as well as by-products thereof.
It is of increasing interest to prepare acyl substituted resorcinols by a method which does not, for instance, encourage the release of environmentally unfriendly organic volatiles.
The instant invention, therefore, is directed to a novel method for making acyl substituted resorcinols while minimizing environmentally unfriendly side effects.